This invention relates to a spinning machine comprising spindles for winding twistings or single yarns and peripheral equipment group of the spindles which are individually driven by an electric motor, and, more particularly to a method of control suitable for use in synchronous drive of electric motors which are individually operated.
Conventionally, a method in which spindles for winding twistings or single yarns and periphery equipment group such as draft rolls or ring rails which work in association with these spindles are driven by a single electric motor via a reducer or a proper driving belt has been in practice. In this equipment configuration, the drive of spindles and that of periphery equipment group of the spindles are conducted in a synchronized manner.
Recently, in order to improve the working efficiency of spindle machines, high speed operation of spindles are planned. In this case, in order to provide high-speed operation of spindles, a method is employed in which each spindle is driven by an individual unit electric motor and high frequency AC power is supplied to these unit motors by a frequency variable power source device. In order to synchronously drive spindles and periphery equipment group of the spindles, a method is taken into consideration in which the above two types of components are driven by the same variable frequency power source device, or a method is taken into consideration in which driving power sources for the above two types of components are individually provided and the ratio of outputs (frequencies) of the two power source devices are controlled to be constant.
Devices relative to such types are exemplified by those disclosed in Japanese Patent Publication No. 32864/1979, Japanese Patent Laid-Open No. 204929/1984 and Japanese Patent Laid-Open No. 155729/1985.